1. Field of the Invention
The present invention relates to an incubator suitable for use in protecting and caring for an immature infant such as a premature baby.
2. Description of the Prior Art
An incubator is used for protecting and caring for an immature or low birth weight infant such as a premature baby, in an optimum environment isolated from the atmosphere. Generally, the incubator comprises a base, a bed mounted on the base, and a transparent hood made of an acrylic resin or the like and covering the bed to define an incubating chamber isolated from the atmosphere. The temperature and humidity of the air within the incubating chamber are regulated so as to make the inside of the incubating chamber be an optimum condition for the infant accommodated therein. For example, the air within the incubating chamber is sucked into an air circulating system provided under the incubating chamber, and, when necessary, fresh air introduced from the outside of the incubator is mixed into the air sucked from the incubating chamber, and then the sucked or mixed air is warmed up and humidified properly, and the thus conditioned air is supplied into the incubating chamber. For this purpose, the air circulating system comprising an air mixing chamber in which the air sucked from the incubating chamber and fresh air introduced from the outside is mixed with each other, an air heating chamber in which the mixed air is warmed up properly, and a humidity regulating unit for regulating the humidity of the air heated in the air heating chamber. They are arranged in that order to constitute the air circulating system.
The humidity regulating unit has a dry passage through which the air warmed in the air heating chamber is supplied into the incubating chamber without being humidified, and a wet passage through which the air warmed in the air heating chamber is supplied into the incubating chamber after being humidified. The dry passage and the wet passage are arranged in parallel to each other along the direction of flow of air and are connected to the air heating chamber. The air warmed in the air heating chamber can be supplied through the dry passage into the incubating chamber without being humidified or through the wet passage into the incubating chamber after being humidified, or a part of the air warmed in the air heating chamber is supplied through the dry passage and the rest of the air is supplied through the wet passage into the incubating chamber.
In the conventional incubator, the dry passage and the wet passage are arranged in parallel to each other under the incubating chamber, and water for humidification is contained directly in the wet passage which is designed as a water tank integrally incorporated into the body of the incubator. Accordingly, to clean the water tank, the hood, bed and a partition plate separating the incubating chamber from the air circulating system must be removed, requiring troublesome cleaning work, which has been a significant disadvantage of the conventional incubator in view of the sanitary management of the incubator.
Furthermore, in the wet passage of the conventional incubator, air is unable to flow in satisfactory contact with water and hence, in some cases, the air is unable to be humidified sufficiently. That is, in the conventional incubator, the wet passage is connected directly to the air heating chamber and air is introduced to flow horizontally from the air heating chamber into the wet passage. Since water is contained in the lower part of the wet passage, the air inlet of the wet passage must be formed above the level of the surface of the water contained in the wet passage, and hence the air introduced from the air heating chamber through the air inlet into the wet passage flows horizontally within the wet passage toward the air outlet. Accordingly, the wet passage of the conventional incubator has the following problems.
The most part of the air introduced through the air inlet into the wet passage flows through the space above the surface of the water contained in the wet passage and only a small part of the air is able to flow in satisfactory contact with the water. Therefore, the water is not warmed up well by the heat of the air so the water is evaporated at a low rate. Consequently, the water flowing through the wet passage is unable to be humidified sufficiently.
To improve the humidifying capability, a conventional wet passage is provided with a plurality of deflectors to make air flow along a zigzag path defined by the deflectors. Since the deflectors increase the effective length of the wet passage and disturb the flow of air, the degree of contact of the air with water is increased to warm up the water to a higher extent and thereby the humidifying capability of the wet passage is improved. However, the deflectors increase the resistance of the wet passage against the flow of air to reduce the flow rate of air, so that the rate of supply of the humidified air into the incubating chamber is reduced.